The disclosure relates, in general, to photoluminescence detection and, more particularly, a system and method for analyses based on phosphorescence lifetime measurements.
In a clinical setting, it is often desirable to monitor a patient's health by measuring tissue gas levels. Tissue-gas analyses are an essential part of modern patient care and are used in the diagnosis and treatment of a number of conditions. In particular, measurement of tissue oxygen concentration is heavily relied upon both for general monitoring of overall patient health and for treatment of specific conditions, such as ischemia, burns, and diabetic foot syndrome.
There are several approaches that may be used to perform blood and tissue gas analyses. Invasive approaches generally involve collecting and analyzing a blood sample drawn from an artery. While blood sample analysis may be performed within minutes and provide accurate results, testing may require a trained practitioner and careful sample handling or results may be inaccurate. Further, invasive testing may not be suitable for repeated analysis or long-term monitoring.
Measurements of tissue oxygen concentration may also be achieved non-invasively. For example, a pulse oximeter is a basic, non-invasive instrument that detects hemoglobin saturation by monitoring the reflectance or absorbance of incident light. By comparison, probe-based systems may be used to measure transcutaneous oxygen (TcpO2) with electrodes or optical sensor foil-based patches that are attached to the sample surface and read out non-invasively using a microscope. In one aspect, TcpO2 systems may require multi-point calibration with specially prepared, well-defined samples. Further, calibrations are generally performed prior to each monitoring period, when changing measuring sites, every four hours, or every time an electrode has been remembraned. In addition, conditions such as room lighting, temperature, and other factors may influence the accuracy of the measurement.
Accordingly, there is a need for ways to perform non-invasive measurements of tissue oxygen concentration that are fast, easily administered, and generally insensitive to the external environment.